Are lake levels up this year? Down? Here's the answer

EDITOR'S NOTE: A version of this article originally appeared on SooToday on Aug. 4. It is being republished here for readers who may have missed it.

If you find yourself lucky enough to be visiting a Sault area camp (aka cottage) this long weekend on one of our Great Lakes, the conversation may turn to the topic of whether or not the lake level is up this year — or down. Or maybe it's just the same.

Everyone seems to have an opinion.

Does someone have to adjust the dock? Will the boat hit a rock? What happened to your beach?

If you'd like to enter this annual debate armed with some facts, read on.

According to the International Lake Superior Board of Control, the lake-wide average water level at the beginning of August on Lake Superior is 14 cm (5.5 in) above the seasonal long-term average (1918-2022). It is also 4 cm (1.6 in) above the level of a year ago.

So that's settled. Lake Superior is up.

Meanwhile, at the beginning of August, the lake-wide average water level of Lake Huron and Lake Michigan (which combined are essentially one giant lake) is 11 cm (4.3 in) above the seasonal long-term average. However, it is 10 cm (3.9 in) below the level of a year ago.

So, Lake Huron is down compared to last year, but still higher than the average as measured over the past 100 or more years.

How much did lake levels change in July?

"Water supply conditions were drier than average in both Lake Superior and Lake Michigan-Huron basins in July," according to the board.

Lake Superior declined by 1 cm (0.4 in.) last month, while the seasonal long-term average pattern is for Lake Superior to actually rise 5 cm (2.0 in) in July, according to the board.

At the same time, Lake Huron-Michigan rose by 1 cm (0.4 in), while the seasonal long-term average pattern for Lake Michigan-Huron tends to be to remain stable in July.

Where are levels headed? It appears to depend on the weather.

It is likely that Lakes Superior and Michigan-Huron are near their seasonal peak water levels, according to the board's report.

If weather and water supply conditions are near average, Lake Superior is expected to remain stable while Lake Michigan-Huron is expected to decline slightly (about 3 cm or 1.2 in) in August.

However, if conditions are wetter than average, Lake Superior may rise by as much as 7 cm (2.8 cm) and Lake Huron-Michigan may rise by as much as 3 cm (1.2 in) in August.

On the other hand, if dry conditions continue, the water level of Lake Superior is expected to decline by as much as 6 cm (2.4 in.), and Lake Michigan-Huron is expected to decline by as much as 9 cm (3.5 in.).

The board added that the gate setting of the Compensating Works at the head of the St. Marys Rapids will be maintained at the current setting in August. At the current flow, "some low-lying areas of Whitefish Island including recreational trails may still be flooded. Users are encouraged to use extreme caution", the board said.

The board said it will continue to adjust the gate settings at the Compensating Works as needed during repairs and maintenance that are ongoing at hydropower plants on the river.  

The board of control is responsible for managing the control works on the St. Marys River and regulating the outflow from Lake Superior into Lake Michigan-Huron. It concludes its report by noting that "under any outflow regulation plan, the ability to regulate the flow through the St. Marys River does not mean that full control of the water levels of Lake Superior and Lake Michigan-Huron is possible. This is because the major factors affecting water supply to the Great Lakes (i.e. precipitation, evaporation, and runoff) cannot be controlled, and are difficult to accurately predict. Outflow management cannot eliminate the risk of extreme water levels from occurring during periods of severe weather and water supply conditions."